Greater Sensitivity to Drought Accompanies Maize Yield Increase in the U.S. Midwest

TLDR

A key question for climate change adaptation is whether existing cropping systems can become less sensitive to climate variations. We use a field‑level dataset of maize and soybean yields in the central United States from 1995 to 2012 to examine changes in drought sensitivity. Yields rose across all stress levels, yet maize drought sensitivity has increased—driven by higher sowing densities and not offset by cultivar improvements or CO₂—showing that agronomic advances raise average yields without reducing field‑scale drought sensitivity.

Abstract

A key question for climate change adaptation is whether existing cropping systems can become less sensitive to climate variations. We use a field-level data set on maize and soybean yields in the central United States for 1995 through 2012 to examine changes in drought sensitivity. Although yields have increased in absolute value under all levels of stress for both crops, the sensitivity of maize yields to drought stress associated with high vapor pressure deficits has increased. The greater sensitivity has occurred despite cultivar improvements and increased carbon dioxide and reflects the agronomic trend toward higher sowing densities. The results suggest that agronomic changes tend to translate improved drought tolerance of plants to higher average yields but not to decreasing drought sensitivity of yields at the field scale.